Search: id:A139589
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%I A139589
%S A139589 1,1,2,3,5,13,89,233,610,987,1597,10946,28657,514229,3524578,9227465,
%T A139589 24157817,39088169,63245986,433494437,1836311903,2971215073,7778742049,
%U A139589 20365011074,591286729879,4052739537881,17167680177565,44945570212853
%N A139589 Fibonacci numbers with Fibonacci number of divisors.
%C A139589 A000005(a(n)) is a Fibonacci number.
%C A139589 For the terms shown here the number of divisors is 1 or 2 or 8. - Emeric 
               Deutsch (deutsch(AT)duke.poly.edu), May 12 2008
%p A139589 A000045 := proc(n) option remember ; coeftayl( x/(1-x-x^2),x=0,n) ; end: 
               isA000045 := proc(n) local a; for a from 0 do if A000045(a) > n then 
               RETURN(false) ; elif A000045(a)=n then RETURN(true) ; fi ; od: end: 
               A000005 := proc(n) numtheory[tau](n) ; end: isA139589 := proc(n) 
               RETURN(isA000045(n) and isA000045(A000005(n))) ; end: for i from 
               1 to 130 do a000045 := A000045(i) ; if isA139589(a000045) then printf("%d,
               ",a000045) ; fi ; od: - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), 
               May 11 2008
%p A139589 with(combinat): with(numtheory): F:={seq(fibonacci(k),k=1..100)}: a:=proc(n) 
               if member(tau(fibonacci(n)),F)=true then fibonacci(n) else end if 
               end proc: seq(a(n),n=1..70); - Emeric Deutsch (deutsch(AT)duke.poly.edu), 
               May 12 2008
%Y A139589 Cf. A000005, A000045, A063375, A133021.
%Y A139589 Sequence in context: A056162 A001685 A074691 this_sequence A152114 A139095 
               A005478
%Y A139589 Adjacent sequences: A139586 A139587 A139588 this_sequence A139590 A139591 
               A139592
%K A139589 nonn
%O A139589 1,3
%A A139589 Omar E. Pol (info(AT)polprimos.com), May 09 2008
%E A139589 More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl) and Emeric 
               Deutsch (deutsch(AT)duke.poly.edu), May 11 2008

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